Hi, I could have almost written that OP myself!
And also agree with alot with what carrietwick says.
I have a 4 month old DS and some days I find it hard to 'entertain' him (was particularly bad when we were snowed in recently for 4 days!!).
In a typical day I will read to him (eg. 'Thats Not My... books'), sing to him (eg. 'Wheels on the Bus'), play with him with one or two of his toys (eg. chime ball, Lamaze Freddie Firefly), let him spend some time in his 'donut' and/or playmat and/or bouncy chair so he can play by himself, and take him out for at least one walk so we both get some fresh air.
I also go to Playgroup 3 times a week and usually meet up with a friend or relative once a week so we both get to see someone different!
When I need to do some housework like washing up or cooking, I will sit him in either his Snug or his pushchair and he will happily watch me. I often talk through what I am doing (I think he just likes to hear my voice -probably doesnt really matter what you say!!).
I sometimes need to check my e-mails (or come onto Mumsnet!!) and will have him on my lap so he can watch what I am doing. Im sure looking at a screen for a short period of time will do him no harm whatsoever - in fact, Im sure he'll be using his own laptop within the next few years!!
I dont let him watch much TV but occassionally I will have it on and he watches it; again I dont see any harm in this. I only do it every so often (maybe 3 times a week for 30 mins or so).
The rest of the time is spent feeding, changing, bathing, dressing, cuddling, and (occassionally) sleeping!! 